1. Technical Field
The present invention relates to trolleys, and more particularly to a folding structure for a trolley, which has an extendable pull rod so as to allow its user to operate the trolley at a proper height.
2. Description of Related Art
Trolleys are handy handling tools widely used in many public places. The conventional trolleys are generally in the form of a two-wheel cart for carrying articles or luggage. Since the places where trolleys used typically have even ground, the trolleys can be easily moved around.
The inventor of the present invention has made many prior inventions about trolleys (e.g. Taiwan Patent Nos. M274293 and 383037). Most of them are focused on the folding structure of trolleys. In addition to the folding structure, what is also important is height adjustment of a trolley's pull rod because only when the height of the pull rod corresponds to a standing user's height, the trolley can be moved smoothly while the user is walking. However, a pull rod with the height facilitating trolley's operation is usually high and less foldable. For addressing this problem. Taiwan Patent No. 360167 discloses a trolley, which has a pair of extension rods provided with an operation button at a proper position. By pressing the operation button, bolts on two links are retracted or expanded to allow inner tubes to move inside the corresponding outer tubes to a proper height and then engage with the bolts. Thereby, the trolley in use can have a proper height that facilitates a user's operation, and can have the height minimized when not in use.
However, the structure for expanding and retracting the pull rod disclosed in the prior patent (i.e. Taiwan Patent No. 360167) is complicated, which may cause difficulty in its assembly and higher manufacturing costs.